While people often use the term depression to describe the sadness or discouraged mood that results from emotionally distressing events, such as a loss of a job or financial hardship, a serious health concern, or death of a loved one, these feelings do not usually represent a mental illness. They are temporary, lasting days rather than weeks or months, and occur in waves that tend to be tied to thoughts or reminders of the distressing event.
According to MerckManuals.com, an online medical reference, clinical depression lasts for more than a couple of weeks and may persist for months or even years. Moreover, it interferes with everyday functioning and decreases interest or pleasure in otherwise enjoyable activities.
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